Linkages between microbial and hydrologic processes in arid and semiarid watersheds
Linkages between microbial and hydrologic processes in arid and semiarid watersheds
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DOI：
10.1890/03-0567
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发表时间：
2005-02-01
期刊：
影响因子：
4.8
通讯作者：
Ludwig, JA
中科院分区：
文献类型：
--
作者：
Belnap, J;Welter, JR;Ludwig, JA
半干旱和干旱环境中的微生物活动与降水的时间、强度和数量密切相关。土壤表面的特性，特别是生物土壤结皮的影响，可以决定水渗入沙漠土壤的数量，位置和时间，这反过来又决定了微生物反应的类型和大小。从这种脉冲产生的营养素然后产生正反馈，因为微生物和植物生物量的增加增强了未来的资源捕获，或者，可能会损失到大气中，更深的土壤或下坡斑块。当降雨强度超过植物间隙或植物斑块的水分入渗能力时，地表水流通过输送水分、土壤和有机质中的养分，将许多不同尺度的分散斑块连接起来。例如，从植物间隙携带的材料通常沉积在相邻植物下。或者，来自这两个斑块的物质可能被带到供给短暂通道的小溪，从那里到季节性间歇，最后到常年河流。这些输入可以保留的河流河岸生态系统或输出的表面流。然而，在较大的常年流，这些材料的输入的命运是混淆的风暴驱动的流量对现存的水生生物群的影响，山洪暴发也可以代表成功的离子引发的干扰流河岸生态系统在广泛的时间尺度。与降水引发微生物反应的高地相反，养分转移可以支持植物吸收和微生物加工的冲洗，由高养分浓度和改变的养分形式（例如，硝酸盐或铵）。不同生态系统组成部分之间联系的性质和强度决定了干旱生态系统的结构和功能。材料的损失是自然过程，但当“养护”系统因人为干扰而“渗漏”，损失超过收益时，就有问题了。
Microbial activity in semiarid and and environments is closely related to the timing, intensity, and amount of precipitation. The characteristics of the soil surface, especially the influence of biological soil crusts, can determine the amount, location, and timing of water infiltration into desert soils, which, in turn, determines the type and size of microbial response. Nutrients resulting from this pulse then create a positive feedback as increases in microbial and plant biomass enhance future resource capture or, alternatively, may be lost to the atmosphere, deeper soils, or downslope patches. When rainfall intensity overwhelms the water infiltration capacity of the plant interspace or the plant patch, overland water flow links otherwise separated patches at many different scales via the transport of nutrients in water, soil, and organic matter. For example, material carried from the plant interspace is often deposited under an adjacent plant. Alternatively, material from both of these patches may be carried to rills that feed ephemeral channels, thence to seasonally intermittent and, finally, perennial streams. These inputs can either be retained by the stream-riparian ecosystem or be exported in surface flow. However, in larger perennial streams, the fate of these material inputs is confounded by the impact of storm-driven flows on the extant aquatic biota, as flash floods can also represent success ion-initiating disturbances to the stream-riparian ecosystem on a wide range of time scales. In contrast to uplands where precipitation initiates the microbial response, nutrient transfers can support a flush of plant uptake and microbial processing, triggered by high nutrient concentrations and changed nutrient form (e.g., nitrate or ammonium). The nature and strength of the linkages between the different ecosystem components define the structure and function of arid ecosystems. Losses of materials are natural processes, but it is problematic when conserving" systems become "leaky" via anthropogenic disturbance and losses exceed gains.